Local Anesthetics
- Local anesthetic agents prevent nerve impulses without causing unconsciousness.
- They bind to sodium channels within nerve fibers, preventing sodium from entering and stabilizing the cell membrane.
- Local anesthetics can be ester-based (e.g., procaine, benzocaine) or amide-based (e.g., lidocaine, bupivacaine).
- Ester local anesthetics are fast-acting but unstable in solution, while amide local anesthetics have a slower onset and longer duration.
- Preservative-free local anesthetics are used for intrathecal injections.

General Anesthetics
- General anesthetics induce a reversible loss of consciousness.
- Inhaled agents, such as isoflurane and sevoflurane, are commonly used for induction and maintenance of general anesthesia.
- Volatile agents should be non-flammable, non-explosive, and lipid-soluble.
- Nitrous oxide is a common adjuvant gas, while halothane has been largely discontinued due to shortcomings.
- Inhaled anesthetics can be used alone or in combination with other medications to maintain anesthesia.

Intravenous Agents
- Barbiturates like thiopental and methohexital are ultra-short-acting and used to induce and maintain anesthesia.
- Benzodiazepines can be used for sedation before or after surgery and to induce and maintain general anesthesia.
- Propofol is commonly used intravenously to induce and maintain general anesthesia.
- Etomidate is primarily used in sick patients due to its favorable physiological effects.
- Ketamine is infrequently used in anesthesia but commonly used in emergency settings and with sick patients.

Comparison of Volatile Agents
- Volatile agents are compared in terms of potency and blood/gas partition coefficient.
- Potency is inversely proportional to the minimum alveolar concentration.
- Lower blood/gas partition coefficient allows for faster titration of anesthesia depth and emergence from anesthesia.
- Isoflurane, desflurane, sevoflurane, and nitrous oxide are agents in widespread current use.
- Enflurane has not gained widespread popularity due to side effects.

Intravenous Opioid Analgesic Agents
- Opioids are rarely used to induce anesthesia due to unreliability and significant side effects.
- They can produce unconsciousness but lack pain relief properties.
- Intravenous opioids are commonly used for pain management during anesthesia.
- Examples of intravenous opioids include morphine, fentanyl, and hydromorphone.
- Opioids should be used with caution due to the risk of respiratory depression.

Muscle Relaxants
- Muscle relaxants are used after a patient is rendered unconscious to facilitate intubation or surgery.
- Hyperkalemia can occur in burn patients, neuromuscular disease, and paralyzed patients, causing life-threatening arrhythmia.
- Muscle aches are common in young muscular patients who mobilize soon after surgery.
- Bradycardia may occur, especially with repeat doses of muscle relaxants.
- Malignant hyperthermia is a potentially life-threatening condition in susceptible patients.
- Suxamethonium apnea is a rare genetic condition that can lead to prolonged neuromuscular blockade.
- Anaphylaxis is a potential complication of muscle relaxant use.
- Histamine release can occur with certain muscle relaxants, such as Atracurium and Mivacurium.
- Anesthesia awareness is a disturbing complication where patients paralyzed may awaken during anesthesia.
- Neurological monitors can help decrease the incidence of anesthesia awareness.

Intravenous Reversal Agents
- Flumazenil reverses the effects of benzodiazepines.
- Naloxone reverses the effects of opioids.
- Neostigmine helps to reverse the effects of non-depolarizing muscle relaxants.
- Sugammadex helps to reverse the effects of non-depolarizing muscle relaxants.

Anesthetic (Wikipedia)

Not to be confused with aesthetics or analgesic.

An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia ⁠— ⁠in other words, to result in a temporary loss of sensation or awareness. They may be divided into two broad classes: general anesthetics, which result in a reversible loss of consciousness, and local anesthetics, which cause a reversible loss of sensation for a limited region of the body without necessarily affecting consciousness.

A wide variety of drugs are used in modern anesthetic practice. Many are rarely used outside anesthesiology, but others are used commonly in various fields of healthcare. Combinations of anesthetics are sometimes used for their synergistic and additive therapeutic effects. Adverse effects, however, may also be increased. Anesthetics are distinct from analgesics, which block only sensation of painful stimuli.